GG/AM/AMPS高吸水性树脂的合成及其性能分析

在没有任何保护气的环境下,用瓜尔胶(GG)、丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为反应原料,N,N′-亚甲基双丙烯酰胺(NMBA)为交联剂,过硫酸钾(KPS)为引发剂,使用水溶液热聚合法合成GG/AM/AMPS高吸水性树脂。采用正交实验法研究了反应条件对树脂吸水率的影响,在最优条件下对树脂的性能进行探究,并对其结构进行表征分析。实验结果表明,当单体摩尔比为n(AM)∶n(AMPS)=1∶1,pH=8,ω(NMBA)=0.08%,ω(KPS)=0.5%,ω(GG)=3.6%时,合成GG/AM/AMPS高吸水性树脂的吸水率达2752g/g。     

静置热聚合法合成AMPS/AM/CMC三元共聚高吸水树脂

在没有氮气保护的作用下,以N,N′-亚甲基双丙烯酰胺(NMBA)为交联剂,以过硫酸铵(APS)为引发剂,采用静置热聚合法合成2-丙烯酰胺基-2-甲基丙磺酸(AMPS)/丙烯酰胺(AM)/羧甲基纤维素钠(CMC)三元共聚高吸水树脂。研究了反应条件对树脂吸水率的影响,并借助FT-IR、TG-DTA和偏光对树脂的分子结构、热稳定性和表面形态进行了分析。实验结果表明:所得树脂的最佳反应条件为:n(AM)∶n(AMPS)=1∶1、ω(APS)=0.45%、ω(CMC)=9%、ω(NMBA)=0.085%和pH=1.2,在此条件下合成的高吸水树脂室温下最大吸蒸馏水倍率为909g/g。     

静置法合成AMPS/AA/AM/MA四元共聚高吸水树脂

以N,N'-亚甲基双丙烯酰胺(NMBA)为交联剂,在没有引发剂和氮气保护的情况下,利用静置法制备以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酸(AA)、丙烯酰胺(AM)、顺丁烯二酸酐(MA)为单体的四元共聚高吸水树脂,通过对反应条件优化,得到了最佳工艺条件:单体配比n(AMPS)∶n(AA)∶n(AM)∶n(MA)=1∶1∶1∶1,ω(NMBA)=0.03%,pH=2.2,在此条件下树脂吸蒸馏水倍率达到533倍。初步对树脂的吸液能力、耐热保水性、吸水速率、以及反复吸液性进行了研究,同时借助FT-IR、TG-DTG和显微镜对其结构、热稳定性及表面形态进行了表征。     

AM/MMA-BX交联型接枝共聚物的合成与表征

以蔗渣木聚糖(BX)为主要原料,过硫酸铵为引发剂,N′,N-亚甲基双丙烯酰胺(MBAM)为交联剂,在水溶液中与丙烯酰胺(AM)、甲基丙烯酸甲酯(MMA)接枝共聚,合成了AM/MMA-BX交联型接枝共聚物。考察了BX与混合单体(AM-MMA)质量比、单体配比、引发剂浓度、反应温度、反应时间、反应体系溶剂用量、交联剂MBAM用量等对单体转化率(C)、接枝率(G)和接枝效率(GE)的影响。实验确定的较佳反应条件为:m(BX)∶m(AM-MMA)=1∶1,单体配比n(AM)∶n(MMA)=2∶1,引发剂浓度0.043mol·L-1,反应温度55℃,反应时间8.0h,m(BX)∶V(溶剂)=3∶25(g/mL),m(BX)∶m(MBAM)=3∶0.07。采用IR,SEM,XRD对蔗渣木聚糖和接枝共聚物的结构进行了表征。IR在1668cm-1、1737cm-1处出现特征峰;SEM显示颗粒表面结构比改性前光滑,没有粗糙和较大的沟壑;XRD说明分子排列的规整性提高,结晶度增加,结晶区域变大。     

反应条件对接枝交联双重改性淀粉胶黏剂性能的影响

以玉米淀粉为原料,过硫酸铵( APS)与亚硫酸氢钠( NaHSO3 )为引发剂,丙烯酰胺( AM)与丙烯酸丁酯(BA)为接枝单体,环氧氯丙烷(ECH)为交联剂,制得了接枝交联双重改性淀粉基木材胶黏剂。 采用红外光谱对样品进行了表征,并研究了 AM 与 BA 质量比、APS 与 NaHSO3 质量比、反应温度、反应时间对淀粉基木材胶黏剂胶合强度及耐水性的影响。 实验结果表明,AM 与 BA 的接枝改性可以提高淀粉基木材胶黏剂胶合强度及耐水性,红外光谱证实 AM 和 BA 与淀粉发生了接枝反应。     

丙烯酸-丙烯酰胺合成树脂的制备及其性能研究

采用水溶液聚合的方法,以丙烯酰胺(AM)和丙烯酸(AA)为单体,以过硫酸钾(KPS)和亚硫酸氢钠为引发剂,N,N′-二甲基双丙烯酰胺(NMBA)为交联剂,来制备丙烯酸-丙烯酰胺合成吸水树脂。研究了其工艺过程并对其性能进行了测试。结果表明:在30℃下,丙烯酸-丙烯酰胺共聚树脂的最佳制备条件为:单体浓度为25%,n(AA)∶n(AM)=4∶1,中和度为75%,交联剂的用量和引发剂的用量分别为单体质量的0.04%和0.3%,所得到的树脂最佳吸纯水倍率及最佳吸0.9%(质量分数)NaCl溶液倍率分别为980g/g和95g/g。     

紫外辐射法制备AM/MA/AMPS/KF四元共聚吸附树脂及性能研究

以N,N,-亚甲基双丙烯酰胺(NMBA)为交联剂,在无氮气保护和不添加任何引发剂条件下,采用紫外辐照法合成魔芋粉(KF)/丙烯酰胺(AM)/马来酸酐(MA)/2-丙烯酰胺基-2-甲基丙磺酸(AMPS)共聚吸附树脂,研究了单体摩尔比、pH、交联剂用量、魔芋粉含量对树脂吸附亚甲基蓝的影响,并借助FT-IR、TG对树脂的结构、热稳定性进行了研究。实验表明:在优化条件下,n(AMPS)∶n(AM)∶n(MA)=2.5∶0.5∶0.4;w(KF)=2.5%,pH=3,w(NMBA)=0.35%,tcuring=5min时合成的树脂对亚甲基蓝的吸附量为104.14mg/g。     

PTA-IA-AMPS三元功能共聚物的合成及缓蚀阻垢性能研究

以马来酸酐(MA)、乙醇胺(EA)、衣康酸(IA)以及2-丙烯酰胺-2-甲基丙烷磺酸(AMPS)为单体,过硫酸铵和次亚磷酸钠为引发剂,采用水溶液自由基聚合制备PTA-IA-AMPS三元功能共聚物。通过正交优化和验证实验确定最佳合成条件。采用静态阻垢法和旋转挂片法分别测试合成产物的阻垢和缓蚀性能。结果表明,共聚单体的摩尔比(n_(IA)∶n_(PTA)∶n_(AMPS))为2.5∶1∶0.1、引发剂过硫酸铵和次亚磷酸钠用量分别为单体总质量的8%和20%、反应温度为90℃且反应时间4 h,合成的PTA-IA-AMPS共聚物性能最佳;用量为30 mg/L时,阻垢率可达90.83%,缓蚀率99.40%,属于抑制阴极为主的阴极型缓蚀剂,性能优良。     

三元共聚高吸水树脂的简易合成

在没有氮气保护和引发剂作用下,以N,N′-亚甲基双丙烯酰胺(NMBA)为交联剂,采用静置热聚合法成功合成了2-丙烯酰胺基-2-甲基丙磺酸(AMPS)/丙烯酰胺(AM)/壳聚糖(CTS)三元共聚高吸水树脂。同时研究了反应条件对树脂吸水倍率的影响,并借助FT-IR对树脂的分子结构进行了分析。实验结果表明,所合成的树脂最佳反应条件为:n(AM)∶n(AMPS)=3∶1,ω(CTS)=2%,ω(NMBA)=0.05%,pH=1.5,固含量为15%。在此条件下合成的高吸水树脂室温下最大吸蒸馏水倍率为1302g/g。     

四烯丙基氯化铵交联的耐高温吸水树脂的研究

采用水溶液聚合法,以丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为单体,四烯丙基氯化铵(TAAC)为交联剂,过硫酸铵(APS)为引发剂,制备了耐高温吸水树脂,考察了单体配比、引发剂和交联剂用量对吸水树脂在高温下吸水性能的影响,并对吸水树脂结构进行扫描电镜分析。研究结果表明,所合成的吸水树脂具有良好的耐高温性能,最佳合成条件:AMPS与AA的质量比为0.22,引发剂、交联剂与单体的物质的量比分别为0.11%、0.14%,此条件下合成的吸水树脂在300℃蒸馏水中的吸水倍率为248g/g。     

Structural and optical properties of AlxOy/Pt/AlxOy multilayer absorber

We report on the microstructure and optical properties of Al_xO_y–Pt–Al_xO_y interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of Al_xO_y. The top and bottom Al_xO_y layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of Al_xO_y. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the Al_xO_y–Pt–Al_xO_y interference-type multilayer stack for use in high temperature solar-thermal applications.     

Optimization of AlxOy/Pt/AlxOy multilayer spectrally selective coatings for solar-thermal applications

Spectrally selective Al_xO_y/Pt/Al_xO_y multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both Al_xO_y layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of Al_xO_y/Pt/Al_xO_y multilayer absorber indicated the Al_xO_y layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively.     

Interfacial microstructure of NiSix/HfO2/SiOx/Si gate stacks

Integration of NiSi_x based fully silicided metal gates with HfO₂ high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi_x film. Ni content varies near the NiSi/HfO_x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi_x/HfO₂ interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi_x/HfO_x was found higher than that of poly-Si/HfO₂, likely due to compositional non-uniformity of NiSi_x. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed.     

Tc trend in high-Tc superconductors

In our previous works, we have shown that most existing ceramic superconductors can be considered to be built of superconductor-semiconductor composite and we have estimated the change in phonon spectrum of the intrinsic superconductor unit if a semiconductor unit is attached to it. Moreover, the proximity effect under the size quantization condition has been examined in the superconductor-semiconductor composite. Each of the stated effects by itself could causeT _c enhancement in general as more semiconductor blocks are added to the system. We extend our study in this paper to analyze the combined actions of phonon spectral change and proximity effect without size quantization condition onT _c variation in members of the Tl₁ series of high-T _c superconductors. Our results indicate that an optimumT _c is obtained if the stated effects are included in the idealized unit cells of the superconductors made up of a superconductor-semiconductor array.     

Anomalous Hall Effect in Sn1?x?yMnxEuyTe and Sn1?x?yMnxEryTe Mixed Crystals

The Anomalous Hall Effect (AHE) was investigated in IV–VI ferromagnetic semimagnetic semiconductors of Sn_1–x Mn _x Te codoped with either Eu or Er. The analysis of experimental data is as follows. Hall resistivity and magnetization showed that AHE coefficient R _s depends on temperature and its value decreases with thetemperature increase. We observe that above ferromagnet–paramagnet transition temperature R _s changes sign. We discuss the possible physical mechanisms responsible for observed temperature dependence of R _s , particularly change of the sign.     

Synthesis of a new perovskite Pb(Li14Nb34)O3

A high-pressure technique was adopted to obtain perovskite-type $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$. A new perovskite $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$ was characterized to have a cubic symmetry with $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 4.069}\text{A}\text{?}$; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement.     

Bulk crystalline BaPb34Bi14O3: A ceramic superconductor

The preparation conditions of the high T_C ceramic superconductor Ba(Pb,Bi)O₃ is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition.     

Electrostriction in Pb (Zn13Nb23)O3

The electrostriction in $\text{Pb (Zn}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP² above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q₁₁ = 1.6·10^?2m⁴/C², Q₁₂ = ?0.86·10^?2m⁴/C², and Q₄₄ = 0.85·10^?2m⁴/C².     

Magnetic,electrical and thermal studies on the V1−xMox02

The monoclinic-to-tetragonal structure transition of oxides V_1?xMo_x0₂ with $\text{0≤}\text{x}\text{≤0.20}$ has been studied by means of DTA, X-ray diffraction, magnetic susceptibility (powder samples) and electrical conductivity (single crystals) measurements within the temperature region 80 K to 400 K. A linear decrease of the transition temperature of 11 K per atom % Mo was observed. The magnetic susceptibility of the low temperature phase was found to be temperature independent paramagnetic for all preparations. Electrical conductivity measurements on the same phase showed crystals with $\text{x}\text{? 0.04}$ to be semiconducting, while a metallic behavior was observed in the region $\text{0.10 ?}\text{x}\text{? 0.14}$.